This is a continuation of the discussion started in the Solar Charge Controller switching from lithium to sealed thread, specifically post 43 and 44. The reason the discussion is moved here is after reviewing my own post (43) it veers off of that thread's topic. If you go back and read that other thread but want to comment on this side topic, do so in this thread!
What I asked DaveH to do is to post the performance of his array. According to the information I gleaned from the other thread, Dave has a Furrion 165W panel (see post 20) paired with a Victron 100/30 SmartSolar controller.
The Furrion panel's specs are below (focus on Vmp, or the expected operating voltage of the panel when paired with an MPPT controller and VoC, the "Open Circuit Voltage").
The hypothesis behind my question to Dave is that since it's known the Victron won't start working until the solar voltage (PV) output of the array is 5V above the battery voltage level, the single Furrion 165W panel's relatively low operating Vmp results in a narrow operating range while charging the battery.
Example: Assume a battery voltage of 13.2vDC in the morning. Further assume shore power is NOT connected (or the converter is turned off). The solar controller won't start working until PV = 18.2vDC. Since it operates at 18.72v, that's a very narrow operating window.
The VictronConnect app records performance, so DaveH sent me the following screenshots as shown below.
TRENDS
HISTORY
What's interesting (looking at the Trends images) is that PV appears to nominally operate around 23vDC. This is nearly the Open Circuit Voltage (VoC) of the panel.
So what's the takeaway? An educated guess: when these screenshots were taken, the camper was plugged into shore power and the converter had already charged the battery, thus there was only a short and low power output from the solar controller before the battery rejected any further charging (short bulk mode, which quickly switched to float).
How did I come to that conclusion? When a battery is fully charged and a solar controller is operating in full sunshine, the resistance of the battery to accepting a charge is so high the solar array sees the equivalent of an open circuit--thus the high Solar Voltage recorded in the screenshots (nearly at VoC instead of Vmp). The guess is supported by the 10Wh yield over an entire day as shown in the History screenshot.
My conclusion is the array's performance cannot be judged based on the data provided. To do a true evaluation of the performance, DaveH will need to remove shore power from the camper (best time is at sundown) when the forecast for the next day promises plenty of sunshine. When shore power is removed, leave a small light on inside the camper to induce a small drain on the battery bank overnight. That should result in a partially-drained battery bank when the sun rises.
Turn off the small light inside the camper in the morning and do not use any items in the camper. Now let the array do all the work of charging the battery.
On the subsequent morning (after a full day with nothing but solar charging the battery), plug the camper back into shore power.
In the VictronConnect app, look at the History and Trend data of the day's array performance when the only source of battery charging power was PV.
DaveH -- I will try this experiment on my camper and will post the results to see if a judgment can be made about the performance based on the Trends and History information. Then, if you're willing, we can see if the methodology can be reproduced on your setup.
More to come in a day or two.
Howard
What I asked DaveH to do is to post the performance of his array. According to the information I gleaned from the other thread, Dave has a Furrion 165W panel (see post 20) paired with a Victron 100/30 SmartSolar controller.
The Furrion panel's specs are below (focus on Vmp, or the expected operating voltage of the panel when paired with an MPPT controller and VoC, the "Open Circuit Voltage").
The hypothesis behind my question to Dave is that since it's known the Victron won't start working until the solar voltage (PV) output of the array is 5V above the battery voltage level, the single Furrion 165W panel's relatively low operating Vmp results in a narrow operating range while charging the battery.
Example: Assume a battery voltage of 13.2vDC in the morning. Further assume shore power is NOT connected (or the converter is turned off). The solar controller won't start working until PV = 18.2vDC. Since it operates at 18.72v, that's a very narrow operating window.
The VictronConnect app records performance, so DaveH sent me the following screenshots as shown below.
TRENDS
HISTORY
What's interesting (looking at the Trends images) is that PV appears to nominally operate around 23vDC. This is nearly the Open Circuit Voltage (VoC) of the panel.
So what's the takeaway? An educated guess: when these screenshots were taken, the camper was plugged into shore power and the converter had already charged the battery, thus there was only a short and low power output from the solar controller before the battery rejected any further charging (short bulk mode, which quickly switched to float).
How did I come to that conclusion? When a battery is fully charged and a solar controller is operating in full sunshine, the resistance of the battery to accepting a charge is so high the solar array sees the equivalent of an open circuit--thus the high Solar Voltage recorded in the screenshots (nearly at VoC instead of Vmp). The guess is supported by the 10Wh yield over an entire day as shown in the History screenshot.
My conclusion is the array's performance cannot be judged based on the data provided. To do a true evaluation of the performance, DaveH will need to remove shore power from the camper (best time is at sundown) when the forecast for the next day promises plenty of sunshine. When shore power is removed, leave a small light on inside the camper to induce a small drain on the battery bank overnight. That should result in a partially-drained battery bank when the sun rises.
Turn off the small light inside the camper in the morning and do not use any items in the camper. Now let the array do all the work of charging the battery.
On the subsequent morning (after a full day with nothing but solar charging the battery), plug the camper back into shore power.
In the VictronConnect app, look at the History and Trend data of the day's array performance when the only source of battery charging power was PV.
DaveH -- I will try this experiment on my camper and will post the results to see if a judgment can be made about the performance based on the Trends and History information. Then, if you're willing, we can see if the methodology can be reproduced on your setup.
More to come in a day or two.
Howard
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